Ice Phoenix

Ice Phoenix came with the Winter Item Pack, sold for 1,299 Robux during the 2017 Christmas Event. The pack is offsale now, so the pet is traded rather than bought. It belongs to the Christmas 2017 item pack, which the Gamepasses page lists as Ice Shard, Ice Phoenix and Blizzard.

Compared with Frostbird

The wiki says Ice Phoenix is similar to Frostbird but is not pixelated. It is thinner and completely blue, with a frost-like look, and two blue fire effects stream from the tips of its wings. Frostbird, by contrast, is the blue retexture of the pixelated Phoenix and was a Lumber Yard reward rather than a pack item.

The three phoenixes

The game has three phoenix pets: Phoenix, Frostbird and Ice Phoenix. This one is the only one that came from a Christmas item pack and not from the 8-Bit Item Pack or a tier list. Its model comes from the Roblox gear Icy Arctic Fowl, according to the trivia on the pet page, so its slim shape is a different base from the pixel style used by the other two.